STK C-E. Overview. Applications. Features. Thick-Film Hybrid IC 2-phase Stepping Motor Driver

Transcription

1 Ordering number : ENA2115 STK C-E Thick-Film Hybrid IC 2-phase Stepping Motor Driver Overview The STK C-E is a hybrid IC for use as a unipolar, 2-phase stepping motor driver with PWM current control. Applications Office photocopiers, printers, etc. Features Built-in opened motor pin detection function (output current OFF). Built-in overcurrent detection function (output current OFF). Built-in overheat detection function (output current OFF). If opened motor pin, over-current, or overheat detection function is activated, the FAULT1 signal (active low) is output. The FAULT2 signal is used to output the result of activation of protection circuit detection at 3 levels. Built-in power on reset function. The motor speed is controlled by the frequency of an external clock signal. 2 phase or 1-2 phase excitation switching function. Using either or both edges of the clock signal switching function. Phase is maintained even when the excitation mode is switched. Rotational direction switching function. Supports schmitt input for 2.5V high level input. Incorporating a current detection resistor (0.141Ω: resistor tolerance ±2%), motor current can be set using two external resistors. The ENABLE pin can be used to cut output current while maintaining the excitation mode. With a wide current setting range, power consumption can be reduced during standby. No motor sound is generated during hold mode due to external excitation current control. Semiconductor Components Industries, LLC, 2013 June, HKPC No. A2115-1/26

2 Specifications Absolute Maximum Ratings at Tc = 25 C Parameter Symbol Conditions Ratings unit Maximum supply voltage 1 V CC max No signal 50 V Maximum supply voltage 2 V DD max No signal -0.3 to +6.0 V Input voltage V IN max Logic input pins -0.3 to +6.0 V Output current 1 I OP max 10μA, 1 pulse (resistance load) 10 A Output current 2 I OH max V DD =5V, CLOCK 200Hz 2.65 A Output current 3 I OF max Pin16 output current 10 ma Allowable power dissipation 1 PdMF max With an arbitrarily large heat sink. Per MOSFET 7.3 W Allowable power dissipation 2 PdPK max No heat sink 3.1 W Operating substrate temperature Tc -20 to +105 C Junction temperature Tj max 150 C Storage temperature Tstg -40 to +125 C Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Allowable Operating Ranges at Ta=25 C Parameter Symbol Conditions Ratings unit Operating supply voltage 1 V CC With signals applied 0 to 46 V Operating supply voltage 2 V DD With signals applied 5±5% V Input high voltage V IH Pins 10, 12, 13, 14, 15, 17 V DD =5±5% 2.5 to V DD V Input low voltage V IL Pins 10, 12, 13, 14, 15, 17 V DD =5±5% 0 to 0.8 V Output current 1 I OH 1 Tc=105 C, CLOCK 200Hz, Continuous operation, duty=100% Output current 2 I OH 2 Tc=80 C, CLOCK 200Hz, Continuous operation, duty=100%, See the motor current (I OH ) derating curve 2.0 A 2.2 A CLOCK frequency f CL Minimum pulse width: at least 10μs 0 to 50 khz Recommended Vref range Vref Tc=105 C 0.14 to 1.38 V Electrical Characteristics at Tc=25 C, VCC=24V, VDD=5.0V Parameter Symbol Conditions min typ max unit V DD supply current I CCO Pin 9 current CLOCK=GND 5 8 ma Output average current* Ioave R/L=1Ω/0.62mH in each phase A FET diode forward voltage Vdf If=1A (R L =23Ω) V Output saturation voltage Vsat R L =23Ω V Input high voltage V IH Pins 10, 12, 13, 14, 15, V Input low voltage V IL Pins 10, 12, 13, 14, 15, V FAULT1 low output voltage V OLF Pin 16 (I O =5mA) V 5V level FAULT leakage current I ILF Pin 16=5V 10 μa FAULT2 opened motor pin detection output voltage FAULT2 Overcurrent detection output voltage FAULT2 Overheat detection output voltage V OF 1 V OF 2 V OF 3 Pin 8 (when all protection functions have been activated) V level input current I ILH Pins 10, 12, 13, 14, 15, 17=5V μa GND level input current I ILL Pins 10, 12, 13, 14, 15, 17=GND 10 μa Vref input bias current I IB Pin 19=1.0V 1 μa PWM frequency fc khz Overheat detection temperature TSD Design guarantee 144 C Drain-to-Source leakage current I DSS V DS =100V, Pins 2, 6, 9, and 18=GND V 1 μa * Maximum value of operating supply voltage 1 (VCC) can not supply to STK C-E, depending on motor current value. Refer to 8. Precautions, etc of Usage Notes. *Ioave values are for when the lead frame of the product is soldered to the mounting substrate. Notes: A fixed-voltage power supply must be used. No. A2115-2/26

3 Package Dimensions unit:mm (typ) STK C-E (20.47) (12.9) 7.2 (5.0) (5.0) (R1.7) (3.5) (5.6) = (20.4) Derating curve of motor current, IOH, vs. STK C-E Operating substrate temperature, Tc Hz 2-phase excitation IOH - Tc Motor current, I OH - A Hold mode Operating Substrate Temperature, Tc- C ITF02548 Notes The current range given above represents conditions when output voltage is not in the avalanche state. If the output voltage is in the avalanche state, see the allowable avalanche energy for STK672-6** series hybrid ICs given in a separate document. The operating substrate temperature, Tc, given above is measured while the motor is operating. Because Tc varies depending on the ambient temperature, Ta, the value of IOH, and the continuous or intermittent operation of IOH, always verify this value using an actual set. The Tc temperature should be checked in the center of the metal surface of the product package. No. A2115-3/26

4 Block Diagram FAULT2 VrefOP A AB B BB VDD=5V 9 MODE1 10 N.C 11 MODE2 17 CLOCK 12 CWB 13 RESETB 14 ENABLE 15 FAULT1 16 Excitation mode selection Phase advance counter Power-on reset FAULT1 FAULT2 signal VDD Latch Circuit Latch Circuit Phase excitation signal generator Vref/4.9 Output open detection Overcurrent detection Current control chopper circuit FAO FAB FBO FBB AI BI F1 F2 F3 F4 R1 R2 2 6 P.G2 P.G1 Overheating detection Latch Circuit Amplifier VSS Vref N.C 18 VSS Vref 19 Sample Application Circuit STK C-E VDD(5V) CLOCK MODE1 MODE2 CWB A AB 2 phase stepping motor driver VCC 24V ENABLE RESETB B BB R01 R03 + C01 at least 100μF FAULT1 FAULT2 R02 C02 Vref 0.1μF N.C P.G2 P.G1 P.GND No. A2115-4/26

5 Precautions [GND wiring] To reduce noise on the 5V system, be sure to place the GND of C01 in the circuit given above as close as possible to Pin 2 and Pin 6 of the hybrid IC. Also, to achieve accurate current settings, be sure to connect Vref GND to the point where P.G1 and P.G2 share a connection. [Input pins] If VDD is being applied, use care that each input pin does not apply a negative voltage less than -0.3V to PG and DO not apply a voltage greater than or equal to VDD voltage. Do not wire by connecting the circuit pattern on the P.C.B side to N.C Pins. shown in the internal block diagram. Apply 2.5V high level input to pins 10, 12, 13, 14, 15, and 17. Since the input pins do not have built-in pull-up resistors, when the open-collector type pins 10, 12, 13, 14, 15, and 17 are used as inputs, a 1 to 20kΩ pull-up resistor (to VDD) must be used. At this time, use a device for the open collector driver that has output current specifications that pull the voltage down to less than 0.8V at Low level (less than 0.8V at Low level when IOL=5mA). [Current setting Vref] If the motor current is temporarily reduced, the circuit given below (STK C-E, 630C-E : IOH>0.2A STK C-E, 640C-E : IOH>0.3A) is recommended. 5V 5V R01 Vref R01 Vref R3 R02 R3 R02 Motor current peak value IOH setting IOH 0 IOH=(Vref 4.9) Rs The value of 4.9 in Equation above represents the Vref voltage as divided by a circuit inside the control IC. Vref=(R02 (R01+R02)) 5V(or 3.3V) Rs is an internal current detection resistor value of the hybrid IC. Rs=0.141Ω when using the STK C-E Rs=0.089Ω when using the STK C-E, -640C-E No. A2115-5/26

6 Input Pin Functions Pin Name Pin No. Function Input Conditions When Operating CLOCK 12 Reference clock for motor phase current switching Operates on the rising edge of the signal (MODE2=H) MODE1 10 Excitation mode selection Low: 2-phase excitation High: 1-2 phase excitation MODE2 17 High: Rising edge Low: Rising and falling edge CWB 13 Motor direction switching Low: CW (forward) High: CCW (reverse) RESETB 14 System reset A reset is applied by a low level Initial state of A and BB phase excitation in the timing charts is set by switching from low to high. ENABLE 15 The A, AB, B, and BB outputs are turned off, and after operation is restored by returning the ENABLE pin to the high level, operation continues with the same excitation timing as before the low-level input. The A, AB, B, and BB outputs are turned off by a lowlevel input. Output Pin Functions Pin Name Pin No. Function Input Conditions When Operating FAULT1 16 Monitor pin used when opened motor pin, over-current detection, or overheat detection function is activated. FAULT2 8 The result of activation of protection circuit detection is output. VrefOP 7 Monitor pin of reference voltage used when opened motor pin detection. Note: See the timing chart for the concrete details on circuit operation. Low level is output when detected. 3 levels output voltage Normal DC voltage output (typ98mv) No. A2115-6/26

7 Timing Charts 2-phase excitation VDD Power On Reset (or RESETB) MODE1 MODE2 CWB CLOCK ENABLE FAO FAB FBO FBB 1-2 phase excitation VDD Power On Reset (or RESETB) MODE1 MODE2 CWB CLOCK ENABLE FAO FAB FBO FBB No. A2115-7/26

8 1-2 phase excitation (CWB) STK C-E VDD Power On Reset (or RESETB) MODE1 MODE2 CWB CLOCK ENABLE FAO FAB FBO FBB 2 phase excitation Switch to 1-2 phase excitation VDD Power On Reset (or RESETB) MODE1 MODE2 CWB CLOCK ENABLE FAO FAB FBO FBB No. A2115-8/26

9 1-2 phase excitation (ENABLE) STK C-E VDD Power On Reset (or RESETB) MODE1 MODE2 CWB CLOCK ENABLE FAO FAB FBO FBB 1-2 phase excitation (Hold operation results during fixed CLOCK) VDD Power On Reset (or RESETB) MODE1 MODE2 CWB CLOCK ENABLE FAO Hold operation FAB FBO FBB No. A2115-9/26

10 2 phase excitation (MODE 2) STK C-E VDD Power On Reset (or RESETB) MODE1 MODE2 CWB CLOCK ENABLE FAO FAB FBO FBB 1-2 phase excitation (MODE 2) VDD Power On Reset (or RESETB) MODE1 MODE2 CWB CLOCK ENABLE FAO FAB FBO FBB No. A /26

11 Usage Notes 1. Input signal functions and timing [ENABLE, CLOCK and power on reset, RESETB (Input signal timing when power is first applied)] The control IC of the driver is equipped with a power on reset function capable of initializing internal IC operations when power is supplied. A 4V typ setting is used for power on reset. Because the specification for the MOSFET gate voltage is 5V±5%, conduction of current to output at the time of power on reset adds electromotive stress to the MOSFET due to lack of gate voltage. To prevent electromotive stress, be sure to set ENABLE=Low while VDD, which is outside the operating supply voltage, is less than 4.75V. In addition, if the RESETB terminal is used to initialize output timing, be sure to allow at least 10μs until CLOCK input. Control IC power (VDD) rising edge 4V typ 3.8V typ Control IC power on reset RESETB signal input No time specification ENABLE signal input CLOCK signal input At least 10μs At least 10μs ENABLE, CLOCK, and RESETB Signals Input Timing [CLOCK (Phase switching clock)] Input frequency: DC to 50kHz Minimum pulse width: 10μs MODE2=1(High) Signals are read on the rising edge. MODE2=0(Low) Signals are read on the rising and falling edges. [CWB (Motor direction setting)] The direction of rotation is switched by setting CWB to 1 (high) or 0 (low). See the timing charts for details on the operation of the outputs. Note: The state of the CWB input must not be changed during the 6.25μs period before and after the rising edge of the CLOCK input. [ENABLE (Forcible on/off control of the A, AB, B, and BB outputs, and hybrid IC internal operation)] ENABLE=1: Normal operation ENABLE=0: Outputs A, AB, B, and BB forced to the off state. If, during the state where CLOCK signal input is provided, the ENABLE pin is set to 0 and then is later restored to the 1 state, the IC will resume operation with the excitation timing continued from before the point ENABLE was set to 0. If sudden stop is applied to the CLOCK signal used for motor rotation, the motor axis may advance beyond the theoretical position due to inertia. To stop at the theoretical position, the SLOW DOWN setting for gradually slowing the CLOCK cycle is required. No. A /26

12 [MODE1 and MODE2 (Excitation mode selection)] MODE1=0: 2-phase excitation MODE2=1: Rising edge of CLOCK MODE1=1: 1-2 phase excitation MODE2=0: Rising and falling edges of CLOCK See the timing charts for details on output operation in these modes. Note: The state of the MODE input must not be changed during the 5μs period before and after the rising edge of the CLOCK input. The CLOCK input must not be changed during the period from when the signal changes from high to low or low to high in MODE1 or MODE2, till when the signal changes from high to low or low to high in CWB. [Configuration of Each Input Pin] <Configuration of the MODE1, MODE2, CLOCK, CWB, ENABLE, and RESETB input pins> <Configuration of the FAULT2 pin> 5V Output pin Pin 8 5V 50kΩ 10kΩ 50kΩ Opened motor pin Input pin 100kΩ 50kΩ Overcurrent VSS Thermal shutdown (Configuration of the buffer is open drain.) All input pins of this driver support schmitt input. Typ specifications at Tc = 25 C are given below. Hysteresis voltage is 0.3V (VIHa-VILa). When rising When falling Input voltage 1.8V typ 1.5V typ VIHa VILa Input voltage specifications are as follows. VIH=2.5V min VIL=0.8V max <Configuration of the Vref input pin> <Configuration of the FAULT1 output pin> Vref/4.9 Output pin Pin 16 5V VSS Amplifier + Input pin Pin 19 VSS Overcurrent Opened motor pin Thermal shutdown No. A /26

13 <FAULT1, FAULT2 output> FAULT1 Output FAULT1 is an open drain output. Low is output if either overcurrent or overheating is detected. FAULT2 output Output is resistance divided (3 levels) and the type of abnormality detected is converted to the corresponding output voltage. Opened motor pin: 10mV (typ) Overcurrent: 2.5V (typ) Overheat: 3.3V (typ) Abnormality detection can be released by a RESETB operation or turning VDD voltage on/off. <VrefOP output pin configuration> 5V Output pin Pin 7 180kΩ 1.3V 17kΩ 1kΩ - + To opened motor pin detection circuit VSS <VrefOP output> To set the motor current detection circuit operates when pin is open, to monitor the reference voltage VrefOP terminal. It is also possible to set any detectable current by connecting an external pull-up resistor to 5V supply. <IOHd by setting pull-up resistor current sensing pin 7 open> When 7 pins open, VrefOP (typ) is 98mV. In this case, detection current IOHd is expressed as follows. VefOP = IOHd Rs (Rs: Current detection resistor) Detection current is 1.1A. Now, detection current greater than 1.1A is IOHdX. Reference voltage VrefOPX is calculated as above. Pull-up resistor Rdx by pin 7 is calculated as follows. RdX = (180 RTX) (180 - RTX) RTX = (5.0V - VrefOPX) (( VrefOPX) ) (RdX and RTX unit is kω) *To disable pin open detection, please connect a 5V pull-up resistor of 10k to 15kΩ. No. A /26

14 2. STK C-E overcurrent detection, overheat detection, and motor terminal open detection functions Each detection function operates using a latch system and turns output off. Because a RESET signal is required to restore output operations, once the power supply, VDD, is turned off, you must either again apply power on reset with VDDON or apply a RESETB=High Low High signal. [Motor terminal open detection] This hybrid IC is equipped with a function for detecting open output terminals to prevent thermal destruction of the MOSFET due to repeated avalanche operation that occurs when an output terminal connected to the motor is open. The open condition is determined by checking the presence or absence of the flyback current that flows in the motor inductance during the off period of the PWM cycle. Detection is performed by using the fact that the flyback current does not flow when a motor terminal is open. Terminal open Current detection resistor voltage Used to see the motor current 0V (GND potential) Used for open detection (Negative current does not flow when the terminal is open.) MOSFET gate signal PWM period When the current level drops, the difference with the GND potential decreases, making detection difficult. The motor current that can be detected by motor terminal open detection is 0.7A or more with the STK C-E. <Notes on the ENABLE high edge> When ENABLE changes from low to high and the STK672-6XXB-E performs constant-current PWM operation that flows a negative current during the 30μs period after the high edge, open detection may activate and stop the driver. The motor current setting voltage Vref must be set so that PWM operation is not performed within a period of 30μs after the high edge. If the motor current setup voltage is set for the rated motor current, PWM operation is not performed during this 30μs period after the high edge, so this is not a problem. In addition, there is no problem with operation that lowers the current setting Vref after the motor rated current is reached as shown in the diagram on the following page. Whether constant-current PWM operation is performed during the 30μs period after the high edge can be judged by substituting the motor L and R values into the formula on the following page. Vref= (R02 (R01+R02)) 5V (or 3.3V) IOH1= (Vref 4.9) Rs IOH1: Motor current value to be set IOH2= (VCC R) (1-e -tr/l ) IOH2: Current value 30μs after the ENABLE high edge Judgment standard: IOH1>IOH2 R01, R02, 5V (or 3.3V): See the Sample Application Circuit documents. Rs: Current detection resistance value (Ω) VCC: Motor supply voltage (V) R: Motor winding resistance (Ω) L: Motor winding inductance (H) There is no problem if the IOH2 obtained by substituting t = 30μs and the motor L and R values is smaller than the current setting value IOH1. No. A /26

15 ENABLE Vref Output current Constant-current PWM operation must not be performed for 30 µs or less. <Connection of capacitors between output pins and GND prohibited> Capacitors must not be connected between the phase A (pin 4), phase AB (pin 5), phase B (pin 3) and phase BB (pin 1) outputs and GND. What happens if capacitors are connected is that open-circuit detection may be triggered by the discharge current of the capacitors when the internal MOSFET is set ON. This current is not an inductance current generated by the motor winding but a capacitor current so a negative current will not flow to the other phase in each pair of phases, possibly causing the driver to shut down. <Excessive external noise> If, when the motor current rises prior to the PWM operation, a spike-shaped current exceeding the Vref-setting current is generated by excessive external noise, for instance, before the current level (0.7A for the STK C-E and 630C-E, 1.1A for the STK C-E and 640C-E motor drivers) at which motor pin open-circuiting can be detected is reached, the internal MOSFET is set OFF. Since the MOSFET has been set OFF before the actual motor current reaches 0.5A (or 0.8A), the level of the negative current subsequently flowing to the other phase in each pair of phases is low, and it may be judged that no negative current is flowing, possibly causing open-circuit detection to be triggered. During normal constant-current PWM operation, the duration of 5.5μs, which is equivalent to 25% of the initial operation in the PWM period, corresponds to the section where the current is not detected, and this ensures that no current is detected for the linking part of the current that is generated in this section. The no-current detection section is not synchronized at the current rise prior to the PWM operation so when a spike-shaped current exceeding the Vref-setting current is generated, the MOSFET is set OFF at the stage where the level of the actual motor current is low. As a result, the level of the negative current subsequently flowing to the other phase in each pair of phases is low, and it may be judged that no negative current is flowing, possibly causing open-circuit detection to be triggered. Motor current Spike-shaped current Vref setting current (IOH) Current level at which opencircuiting is detected No-current detection time (5.5μs typ) PWM period No. A /26

16 [Over current detection] This hybrid IC is equipped with a function for detecting overcurrent that arises when the motor burns out or when there is a short between the motor terminals. Over current detection occurs at 3.5A typ with the STK C-E. and -632C-E. Current when motor terminals are shorted Set motor current, IOH PWM period MOSFET all OFF Over current detection IOH max No detection interval (5.5μs typ) 5.5μs typ Normal operation Operation when motor pins are shorted Over current detection begins after an interval of no detection (a dead time of 5.5μs typ) during the initial ringing part during PWM operations. The no detection interval is a period of time where over current is not detected even if the current exceeds IOH. [Overheat detection] Rather than directly detecting the temperature of the semiconductor device, overheat detection detects the temperature of the aluminum substrate (144 C typ). Within the allowed operating range recommended in the specification manual, if a heat sink attached for the purpose of reducing the operating substrate temperature, Tc, comes loose, the semiconductor can operate without breaking. However, we cannot guarantee operations without breaking in the case of operations other than those recommended, such as operations at a current exceeding IOH max that occurs before over current detection is activated. No. A /26

17 3. Calculating STK C-E HIC Internal Power Loss STK C-E The average internal power loss in each excitation mode of the STK C-E can be calculated from the following formulas. Each excitation mode 2-phase excitation mode 2PdAVex=2 Vsat 0.5 CLOCK IOH t2+0.5 CLOCK IOH (Vsat t1+vdf t3) 1-2 Phase excitation mode 1-2PdAVex=2 Vsat 0.25 CLOCK IOH t CLOCK IOH (Vsat t1+vdf t3) Motor hold mode HoldPdAVex= (Vsat+Vdf) IOH Vsat: Combined voltage of Ron voltage drop + current detection resistance Vdf: Combined voltage of the FET body diode + current detection resistance CLOCK: Input CLOCK (CLOCK pin signal frequency) t1, t2, and t3 represent the waveforms shown in the figure below. t1: Time required for the winding current to reach the set current (IOH) t2: Time in the constant current control (PWM) region t3: Time from end of phase input signal until inverse current regeneration is complete IOH 0A t1 t2 t3 Motor COM Current Waveform Model t1= (-L/(R+0.33)) ln (1-((R+0.33)/VCC) IOH) t3= (-L/R) ln ((VCC+0.33)/(IOH R+VCC+0.33)) VCC: Motor supply voltage (V) L: Motor inductance (H) R: Motor winding resistance (Ω) IOH: Motor set output current crest value (A) Relationship of CLOCK, t1, t2, and t3 in each excitation mode 2-phase excitation mode: t2= (2/CLOCK) - (t1+t3) 1-2 phase excitation mode: t2= (3/CLOCK) -t1 For Vsat and Vdf, be sure to substitute values from the graphs of Vsat vs. IOH and Vdf vs. IOH while the set current value is IOH. Then, determine whether a heat sink is required by comparing with the graph of ΔTc vs. Pd based on the average HIC power loss calculated. When designing a heat sink, refer to the section Thermal design found on the next page. The average HIC power loss, PdAV, described above does not have the avalanche s loss. To include the avalanche s loss, be sure to add Equation (2), STK672-6** Allowable Avalanche Energy Value to PdAV above. When using this IC without a fin always check for temperature increases in the set, because the HIC substrate temperature, Tc, varies due to effects of convection around the HIC. No. A /26

18 STK C-E Output saturation voltage, Vsat - Output current, IOH 1.0 Vsat - IOH Output saturation voltage, Vsat - V Tc=105 C 25 C Output current, I OH - A ITF02571 STK C-E Forward voltage, Vdf -Output current, IOH 1.4 Vdf- IOH Forward voltage, Vdf - V Tc=25 C 105 C Output current, I OH - A ITF02572 Substrate temperature rise, ΔTc (no heat sink) - Internal average power dissipation, PdAV 80 ΔTc - PdAV Substrate temperature rise, ΔTc - C Hybrid IC internal average power dissipation, PdAV - W ITF02551 No. A /26

19 4. STK C-E Allowable Avalanche Energy Value STK C-E (1) Allowable Range in Avalanche Mode When driving a 2-phase stepping motor with constant current chopping using an STK672-6** Series hybrid IC, the waveforms shown in Figure 1 below result for the output current, ID, and voltage, VDS. VDSS: Voltage during avalanche operations VDS IOH: Motor current peak value IAVL: Current during avalanche operations I D tavl: Time of avalanche operations ITF02557 Figure 1 Output Current, ID, and Voltage, VDS, Waveforms 1 of the STK672-6** Series when Driving a 2-Phase Stepping Motor with Constant Current Chopping When operations of the MOSFET built into STK672-6** Series ICs is turned off for constant current chopping, the ID signal falls like the waveform shown in the figure above. At this time, the output voltage, VDS, suddenly rises due to electromagnetic induction generated by the motor coil. In the case of voltage that rises suddenly, voltage is restricted by the MOSFET VDSS. Voltage restriction by VDSS results in a MOSFET avalanche. During avalanche operations, ID flows and the instantaneous energy at this time, EAVL1, is represented by Equation (1). EAVL1=VDSS IAVL 0.5 tavl (1) VDSS: V units, IAVL: A units, tavl: sec units The coefficient 0.5 in Equation (1) is a constant required to convert the IAVL triangle wave to a square wave. During STK672-6** Series operations, the waveforms in the figure above repeat due to the constant current chopping operation. The allowable avalanche energy, EAVL, is therefore represented by Equation (2) used to find the average power loss, PAVL, during avalanche mode multiplied by the chopping frequency in Equation (1). PAVL=VDSS IAVL 0.5 tavl fc (2) fc: Hz units (fc is set to the PWM frequency of 50kHz.) For VDSS, IAVL, and tavl, be sure to actually operate the STK672-6** Series and substitute values when operations are observed using an oscilloscope. Ex. If VDSS=110V, IAVL=1A, tavl=0.2μs when using a STK C-E driver, the result is: PAVL= =0.28W VDSS=110V is a value actually measured using an oscilloscope. The allowable loss range for the allowable avalanche energy value, PAVL, is shown in the graph in Figure 3. When examining the avalanche energy, be sure to actually drive a motor and observe the ID, VDSS, and tavl waveforms during operation, and then check that the result of calculating Equation (2) falls within the allowable range for avalanche operations. No. A /26

20 (2) ID and VDSS Operating Waveforms in Non-avalanche Mode Although the waveforms during avalanche mode are given in Figure 1, sometimes an avalanche does not result during actual operations. Factors causing avalanche are listed below. Poor coupling of the motor s phase coils (electromagnetic coupling of A phase and AB phase, B phase and BB phase). Increase in the lead inductance of the harness caused by the circuit pattern of the P.C. board and motor. Increases in VDSS, tavl, and IAVL in Figure 1 due to an increase in the supply voltage from 24V to 36V. If the factors above are negligible, the waveforms shown in Figure 1 become waveforms without avalanche as shown in Figure 2. Under operations shown in Figure 2, avalanche does not occur and there is no need to consider the allowable loss range of PAVL shown in Figure 3. VDS IOH: Motor current peak value ID ITF02558 Figure 2 Output Current, ID, and Voltage, VDS, Waveforms 2 of the STK672-6** Series when Driving a 2-Phase Stepping Motor with Constant Current Chopping Figure 3 Allowable Loss Range, PAVL-IOH During STK C-E Avalanche Operations Average power loss in the avalanche state, PAVL- W PAVL - IOH 105 C Tc=80 C Motor phase current, IOH - A ITF02573 Note: The operating conditions given above represent a loss when driving a 2-phase stepping motor with constant current chopping. Because it is possible to apply 2.6W or more at IOH=0A, be sure to avoid using the MOSFET body diode that is used to drive the motor as a zener diode. No. A /26

21 5. Thermal design STK C-E [Operating range in which a heat sink is not used] Use of a heat sink to lower the operating substrate temperature of the HIC (Hybrid IC) is effective in increasing the quality of the HIC. The size of heat sink for the HIC varies depending on the magnitude of the average power loss, PdAV, within the HIC. The value of PdAV increases as the output current increases. To calculate PdAV, refer to Calculating Internal HIC Loss for the STK C-E in the specification document. Calculate the internal HIC loss, PdAV, assuming repeat operation such as shown in Figure 1 below, since conduction during motor rotation and off time both exist during actual motor operations, IO1 Motor phase current (sink side) IO2 0A -IO1 T1 T2 T3 T0 Figure 1 Motor Current Timing T1: Motor rotation operation time T2: Motor hold operation time T3: Motor current off time T2 may be reduced, depending on the application. T0: Single repeated motor operating cycle IO1 and IO2: Motor current peak values Due to the structure of motor windings, the phase current is a positive and negative current with a pulse form. Note that figure 1 presents the concepts here, and that the on/off duty of the actual signals will differ. The hybrid IC internal average power dissipation PdAV can be calculated from the following formula. PdAV= (T1 P1+T2 P2+T3 0) TO (I) (Here, P1 is the PdAV for IO1 and P2 is the PdAV for IO2) If the value calculated using Equation (I) is 1.5W or less, and the ambient temperature, Ta, is 60 C or less, there is no need to attach a heat sink. Refer to Figure 2 for operating substrate temperature data when no heat sink is used. [Operating range in which a heat sink is used] Although a heat sink is attached to lower Tc if PdAV increases, the resulting size can be found using the value of θc-a in Equation (II) below and the graph depicted in Figure 3. θc-a= (Tc max-ta) PdAV (II) Tc max: Maximum operating substrate temperature =105 C Ta: HIC ambient temperature Although a heat sink can be designed based on equations (I) and (II) above, be sure to mount the HIC in a set and confirm that the substrate temperature, Tc, is 105 C or less. The average HIC power loss, PdAV, described above represents the power loss when there is no avalanche operation. To add the loss during avalanche operations, be sure to add Equation (2), Allowable STK672-6** Avalanche Energy Value, to PdAV. No. A /26

22 Figure 2 Substrate temperature rise, ΔTc (no heat sink) - Internal average power dissipation, PdAV 80 ΔTc - PdAV Substrate temperature rise, ΔTc - C Hybrid IC internal average power dissipation, PdAV - W ITF02553 Figure 3 Heat sink area (Board thickness: 2mm) - θc-a Heat sink thermal resistance, θc-a - C/W θc-a - S With no surface finish With a flat black surface finish Heat sink area, S - cm 2 ITF Mitigated Curve of Package Power Loss, PdPK, vs. Ambient Temperature, Ta Package power loss, PdPK, refers to the average internal power loss, PdAV, allowable without a heat sink. The figure below represents the allowable power loss, PdPK, vs. fluctuations in the ambient temperature, Ta. Power loss of up to 3.1W is allowable at Ta=25 C, and of up to 1.75W at Ta=60 C. Allowable power dissipation, PdPK(no heat sink) - Ambient temperature, Ta 3.5 PdPK - Ta Allowable power dissipation, PdPK - W Ambient temperature,ta - C ITF02511 No. A /26

23 7. Example of Stepping Motor Driver Output Current Path (1-2 phase excitation) 2-phase stepping motor IOA IOAB VDD=5V 9 MODE1 10 N.C 11 MODE2 17 CLOCK 12 CWB 13 RESETB 14 ENABLE 15 FAULT1 16 Excitatin mode setting Phase advnce counter Power on reset FAULT1, FAULT2 signal Latch Latch VDD Phase excitation signal generation Opened motor pin detection Over current detection Chopper circuit Vref/4.9 FAULT2 8 VrefOP 7 FAO FAB FBO FBB AI BI A AB B BB F1 F2 F3 F4 R1 R2 P.G2 2 P.G1 6 VCC 24V C02 at least 100μF P.GND Over heat detection Latch Amp VSS Vref N.C Vref VSS CLOCK Phase A output current IOA PWM operations Phase AB output current IOAB When PWM operations of IOA are OFF, for IOAB, negative current flows through the parasitic diode, F2. When PWM operations of IOAB are OFF, for IOA, negative current flows through the parasitic diode, F1. No. A /26

24 8. Other Notes on Use In addition to the Notes indicated in the Sample Application Circuit, care should also be given to the following contents during use. (1) Allowable operating range Operation of this product assumes use within the allowable operating range. If a supply voltage or an input voltage outside the allowable operating range is applied, an overvoltage may damage the internal control IC or the MOSFET. If a voltage application mode that exceeds the allowable operating range is anticipated, connect a fuse or take other measures to cut off power supply to the product. (2) Input pins If the input pins are connected directly to the PC board connectors, electrostatic discharge or other overvoltage outside the specified range may be applied from the connectors and may damage the product. Current generated by this overvoltage can be suppressed to effectively prevent damage by inserting 100Ω to 1kΩ resistors in lines connected to the input pins. Take measures such as inserting resistors in lines connected to the input pins. (3) Power connectors If the motor power supply VCC is applied by mistake without connecting the GND part of the power connector when the product is operated, such as for test purposes, an overcurrent flows through the VCC decoupling capacitor, C1, to the parasitic diode between the VDD of the internal control IC and GND, and may damage the power supply pin block of the internal control IC. To prevent destruction in this case, connect a 10Ω resistor to the VDD pin, or insert a diode between the VCC decoupling capacitor C1 GND and the VDD pin. Overcurrent protection measure: Insert a resistor. 5V Reg. VDD=5V 9 V DD FAO A 4 AB 5 B 3 BB 1 F1 F2 F3 F4 MODE1 CLOCK CWB RESETB ENABLE MODE2 FABO FBO FBBO AI BI Vref R1 R2 GND 2 6 C1 V CC 24V Reg. FAULT1 Vref VSS 18 N.C open Overcurrent protection measure: Insert a diode. Over-current path (4) Input Signal Lines 1) Do not use an IC socket to mount the driver, and instead solder the driver directly to the PC board to minimize fluctuations in the GND potential due to the influence of the resistance component and inductance component of the GND pattern wiring. 2) To reduce noise caused by electromagnetic induction to small signal lines, do not design small signal lines (sensor signal lines, and 5V or 3.3V power supply signal lines) that run parallel in close proximity to the motor output line A (Pin 4), AB (Pin 5), B (Pin 3), or BB (Pin 1) phases. 3) Pin 11 of this product are N.C pins. Do not connect any wiring to these pins. No. A /26

25 (5) When mounting multiple drivers on a single PC board When mounting multiple drivers on a single PC board, the GND design should mount a VCC decoupling capacitor, C1, for each driver to stabilize the GND potential of the other drivers. The key wiring points are as follows. 5V 24V Input Signals 9 IC1 Motor 1 Input Signals 9 IC2 Motor 2 Input Signals 9 IC3 Motor GND GND Short Thick and short Thick (6) VCC operating limit When the output (for example F1) of a 2-phase stepping motor driver is turned OFF, the AB phase back electromotive force eab produced by current flowing to the paired F2 parasitic diode is induced in the F1 side, causing the output voltage VFB to become twice or more the VCC voltage. This is expressed by the following formula. VFB = VCC + eab = VCC + VCC + IOH RM + Vdf (1.5 V) VCC: Motor supply voltage, IOH: Motor current set by Vref Vdf: Voltage drop due to F2 parasitic diode and current detection resistor R1, RM: Motor winding resistance value Using the above formula, make sure that VFB is always less than the MOSFET withstand voltage of 100V. This is because there is a possibility that operating limit of VCC falls below the allowable operating range of 46V, due to the RM and IOH specifications. VCC VCC A phase The pass of drain current AB phase Eab is induced by inducing M. A phase AB phase eab The pass of negative current F1 ON M F2 OFF VFB VCC eab F1 OFF M F2 OFF R1 GND R1 GND The oscillating voltage in excess of VFB is caused by LCRM (inductance, capacitor, resistor, mutual inductance) oscillation that includes micro capacitors C, not present in the circuit. Since M is affected by the motor characteristics, there is some difference in oscillating voltage according to the motor specifications. In addition, constant voltage drive without constant current drive enables motor rotation at VCC 0V. No. A /26

26 ON Semiconductor and the ON logo are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of SCILLC s product/patent coverage may be accessed at SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitabilityof its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. Typical parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including Typicals must be validated for each customer application by customer s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PS No. A /26